Vortex Induced VIBRATION Model Test for Step Riser configuration

2014 ◽  
Author(s):  
Yucheng Hou ◽  
Jiabei Yuan ◽  
John Zhang ◽  
Zhimin Tan
Keyword(s):  
Model Test ◽  
Vortex Induced Vibration ◽  
Vibration Model

scholarly journals VIV Excitation Competition Between Bare and Buoyant Segments of Flexible Cylinders

2013 ◽  
Author(s):  
Zhibiao Rao ◽  
J. Kim Vandiver ◽  
Vikas Jhingran
Keyword(s):  
Model Test ◽  
Practical Problem ◽  
Excitation Frequency ◽  
Ocean Basin ◽  
Recent Model ◽  
Total Amplitude ◽  
Vortex Induced Vibration ◽  
Pipe Model ◽  
Exploration And Production ◽  
Different Diameters

This paper addresses a practical problem: “Under which coverage of buoyancy modules, would the Vortex Induced Vibration (VIV) excitation on buoyant segments dominate the response?” This paper explores the excitation competition between bare and buoyant segments of a 38 meter long model riser. The source of data is a recent model test, conducted by SHELL Exploration and Production at the MARINTEK Ocean Basin in Trondheim Norway. A pipe model with five buoyancy configurations was tested. The results of these tests show that (1) the excitation on the bare and buoyant regions could be identified by frequency, because the bare and buoyant regions are associated with two different frequencies due to the different diameters; (2) a new phenomenon was observed; A third frequency in the spectrum is found not to be a multiple of the frequency associated with either bare or buoyancy regions, but the sum of the frequency associated with bare region and twice of the frequency associated with buoyancy region; (3) the contribution of the response at this third frequency to the total amplitude is small; (4) the power dissipated by damping at each excitation frequency is the metric used to determine the winner of excitation competition. For most buoyancy configurations, the excitation on buoyancy regions dominates the VIV response; (5) a formula is proposed to predict the winner of the excitation competition between bare and buoyant segments for a given buoyancy coverage.

A vortex-induced vibration model for the fatigue analysis of a marine drilling riser

2017 ◽  
Vol 12 (sup1) ◽  
pp. S280-S287 ◽  
Author(s):  
Jing Xu ◽  
Dongshi Wang ◽  
Hui Huang ◽  
Menglan Duan ◽  
Jijun Gu ◽  
...  
Keyword(s):  
Fatigue Analysis ◽  
Vortex Induced Vibration ◽  
Vibration Model

scholarly journals The Effect of Exposure Length on Vortex Induced Vibration of Flexible Cylinders

2012 ◽  
Author(s):  
Zhibiao Rao ◽  
J. Kim Vandiver ◽  
Vikas Jhingran ◽  
Octavio Sequeiros
Keyword(s):  
Strouhal Number ◽  
Model Test ◽  
Traveling Wave ◽  
Practical Problem ◽  
Recent Model ◽  
Response Frequency ◽  
Vortex Induced Vibration ◽  
Pipe Model ◽  
Exploration And Production ◽  
Exposure Length

This paper addresses a practical problem: “What portion of fairing or strake coverage may be lost or damaged, before the operator must take corrective measures?” This paper explores the effect of lost fairings (the exposure length) on Vortex-Induced Vibration (VIV) of flexible cylinders. The source of data is a recent model test, conducted by SHELL Exploration and Production. A 38m long pipe model with varying amounts of fairings was tested. Response as a function of percent exposure length is reported. Unexpected results are also reported: (i) the flexible ribbon fairings used in the experiment did not suppress VIV at speeds above 1 m/s; (ii) Above 1 m/s, a competition was observed between VIV excited in the faired and bare regions of the cylinder, (iii) Unusual traveling wave behavior was documented—waves generated in the bare region periodically changed direction, and exhibited variation in VIV response frequency. The results of these tests showed that (1) the excitation on the bare and faired regions could be identified by frequency, because the faired region exhibited a much lower Strouhal number; (2) as expected, the response to VIV on the bare region increased with exposure length; (3) the response to VIV on the faired region decreased with exposure length.

scholarly journals An Experimental Evaluation of Vortex-Induced Vibration of a Riser Bundle With Gaps

2009 ◽  
Author(s):  
J. Kim Vandiver ◽  
Yongming Cheng ◽  
Vivek Jaiswal ◽  
Aditi Sheshadri ◽  
Alan Yu
Keyword(s):  
Free Vibration ◽  
Model Test ◽  
Flow Direction ◽  
Angle Of Attack ◽  
Cross Flow ◽  
Test Results ◽  
Vortex Induced Vibration ◽  
Towing Tank ◽  
Helical Strakes ◽  
Rigid Model

VIV model test results are presented for a bundle of three parallel pipes all lying in the same plane, similar to a riser with large kill and choke lines. The rigid model was attached to a spring-mounted frame in the MIT towing tank. The horizontal model was towed in the tank and allowed to respond in free vibration to vortex-induced vibration in the cross-flow direction. The angle of attack of the model was varied from 0 to 90 degrees. The model was tested with and without helical strakes. Without strakes the model exhibited significant vibration at 0 and 90 degrees angle of attack. Strakes suppressed VIV at all angles of attack.

scholarly journals Modelling Risers With Partial Strake Coverage

2011 ◽  
Author(s):  
Themistocles L. Resvanis ◽  
J. Kim Vandiver
Keyword(s):  
Experimental Data ◽  
Test Data ◽  
Model Test ◽  
Vortex Induced Vibration ◽  
Partial Coverage ◽  
Prediction Program ◽  
New Methods ◽  
Helical Strakes

This paper compares model test data for risers with partial strake coverage to predictions made with the Vortex-Induced Vibration (VIV) prediction program SHEAR7 Versions 4.5 and 4.6. It is shown that new features in Version 4.6 substantially enhance the capability for predicting the VIV response of risers with partial coverage. Experimental data is taken from two large L/D tests: the NDP 38 m long riser tests and the Deepstar-Miami, 500 foot long riser. New methods are described for modeling risers partially covered with helical strakes. Key SHEAR7 parameters are recommended, based on parametric investigations to calibrate the model against the available experimental data. Recommended modeling procedures are described so as to facilitate implementation by SHEAR7 users in their VIV modeling tasks.

scholarly journals Experimental investigation on coupled cross-flow and in-line vortex-induced vibration responses of two staggered circular cylinders

2020 ◽  
pp. 147509022090747
Author(s):  
Cheng Zhang ◽  
Zhuang Kang ◽  
Yeping Xiong ◽  
Shangmao Ai ◽  
Gang Ma
Keyword(s):  
Model Test ◽  
Flow Direction ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Amplitude Curve ◽  
Vortex Induced Vibration ◽  
Double Peaks ◽  
Gap Ratio ◽  
Vibration Responses ◽  
The Cross

In order to better understand the vortex-induced vibration mechanism of multiple cylinders, this article takes a relatively simple case of two staggered circular cylinders as the embarkation point and investigates their vortex-induced vibration characteristics by model test. The experimental Reynolds number ranges from 22,000 to 88,000. The in-line gap L is set as 3.0 D, 3.6 D, 4.2 D and 5.5 D in turn, and the cross-flow gap T is set as 0.7 D, 1.1 D, 1.5 D, 1.9 D, 2.3 D and 2.7 D, respectively. By measuring the vibrating response in model test, the response differences between the two staggered cylinders and the isolated cylinder and the effects of the gaps are discussed. The results indicate that the variation trend of response of the upstream cylinder with reduced velocity is basically similar to that of the isolated cylinder. However, the downstream cylinder shows some great differences. When the in-line gap ratio L/ D is 3.6, the cross-flow amplitude curve of downstream cylinder changes from “single peak” to “double peaks” with the increase in cross-flow gap ratio T/ D, and in-line amplitude curve even shows four different kinds of forms. When L/ D is increasing, maximum amplitudes of the downstream cylinder in two directions also show an increasing trend, and the wake galloping phenomenon even appears in some conditions. Generally, the case of staggered cylinders is a generalized combination of two circular cylinders in tandem and side-by-side arrangements, and this article has extended the research scope of the double-cylinder vortex-induced vibration to arbitrary flow direction.

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